Hydraulic governor compensation system



HYDRAULIC GOVERNOR COMPENSATION SYSTEM Filed Sept. 27, 1955 '[III I N VEN TOR.

A; BERT G. MASSEY $5M, MMr @eaa ATTORNEYS..

United States Patent HYDRAULIC GDVERNOR CQMPENSATION SYSTEM Albert G. Massey, Watertown, N. Y., assignor, by mesne assignments, to Curtiss-Wright Corporation, New York, N. Y., a corporation of Delaware Application September 27, 1955, Serial No. 536,931

Claims. (Cl. 121-42) This invention relates to hydraulic governors for speed control and analogous uses.

The present invention relates generally to hydraulic governors of the type wherein the primary speed measuring element, a conventional flyball mechanism, connects directly with a pilot valve and, upon speed changes, moves the position of the latter, which in turn provides operating hydraulic fluid to an actuating piston and cylinder arrangement, the latter usually having connection with the control throttle of the prime mover, in cases where the hydraulic governor installation is serving to regulate the speed of such prime mover.

A practical hydraulic governor of the general type here under consideration must include compensating means in one form or another, such compensating means being provided to retard governor response and thereby avoid undue hunting during a correcting operation by the governor. The degree of compensation of governors of this general class varies according to requirements.

\Vhere the compensating arrangement exerts a strong retarding influence the governor is naturally slower in its response to a speed change, that is to say, it is slower to produce an actual throttle change upon a speed change in the prime mover. in converse cases the compensation is termed weak, that is there is a lesser retarding influence effected by the compensating arrangement and the governor, while quicker to respond to a given speed change, is more apt to produce hunting in the case of speed changes of considerable degree.

In the present invention a fluid pressure chamber is established which is compressed or expanded directly by movements of the pilot valve and by a compensating piston, both the pilot valve piston and the compensating piston communicating constantly with such fluid chamber. According to the present invention resilient push-pull means connect between the power piston and the compensating piston whereby movements of the former are not positively reproduced in the latter but are applied thereto in the form of resilient biasing forces.

Accordingly the compensating arrangement of the present invention comprises, in one piston and cylinder device, a basic compensating system and a combined accumulator and proportioning surge chamber arrangementi Furthermore, in the arrangement of the present invention the operating connection between the power piston and the resilient biasing means of the compensating piston is provided with an adjustable ratio operating connection, whereby the proportion of resilient bias which is imparted to the compensating piston by the power piston may be selec-' tively adjusted to vary the resultant compensating piston stroke resulting from a given power'piston movement. This provides a magnitude" adjustment which determines the proportion of power piston adjustment for a given load change and thus permits accurate matching of the governor to any engine or device or system to be governed.

The compensating system thus established comprises, under normal operating conditions, a closed fluid system 2 save only for a leakage needle valve or similar adjustably reduced orifice which acts as a dashpot'regulator directly upon the pilot valve in resistance to initial movement thereof.

Secondly, the needle valve acts as a bypass to proportion the rate of time at which compensating fluid will act to close the pilot valve and thus proportions the degree of corrective movement of the power piston upon displacement of the pilot valve. Thirdly, the needle valve times the speed with which the pilot valve moves back to neutral in proportion to the speed of response of the engine so that the pilot valve will not move to open in the opposite direction under the pressure developed by the compensating piston.

In the general compensating arrangement of the present invention means are provided for acting in cooperation with the pilot valve fluid chamber and the compensating fluid chamber to provide a surge chamber both to serve as a pressure accumulator and to serve as a proportioning device to determine the degree of initial corrective movement to be made by the power piston in response to pilot valve displacement.

Various other aspects of novelty are referred to and pointed out in detail in the following detailed specification, taken in conjunction with the accompanying drawing. It is to be understood that the principles of the present invention are not limited to the precise form set forth by way of example, but only as defined in the appended claims.

The single figure of the drawing is a general schematic view of one form of the hydraulic governor'of the present invention.

In the form of governor illustrated by way of example in the drawing the numeral 10 designates a shaft connectible with the engine or other device or system to be governed. The purpose and effect of the governor system is to maintain a constant'velocity of shaft 10 despite changes in load on the engine being governed or changes in other conditions which tend to vary the velocity of shaft 10 in other adaptations. Where a governor operates.

to maintain a constant velocity of shaft 19 despite differ ences in load on the apparatus being governed, for instance, the governor is said to be isochronous;

In the form of the invention set forth 'herein by way of example the governing adjustment of the engine or other device or system being governed is accomplished by rotating or oscillating a shaft designated 11 in the drawing and, in the case of an engine, shaft 11 may be connected with the throttle valve orother fuel control means as by means of an arm 12. In the case of engine governing operation the load on the engine is reflected in the angular setting of shaft 11.

The flyweight head and the hydraulic fluid system which cooperates therewith operates in a housing 14 and comprises a shaft or sleeve 15 which rotates in a suitable bore in housing 14 and, in the present instance, is fixed directly to shaft 10 and may comprise an extension thereof, the shaft 10 being driven by the engine being governed.

Shaft 15 is bored to receive a pilot valve 16 which has axially spaced generally cylindrical valve heads 17 and 18 and is formed at its upper end with an enlargement 19. A pair of fiyweights 20 are pivoted as at 21 to yoke formations 22 formed upon a flyweight yoke collar 23 friction means whereby the upper end of the spring may rotate freely with pilot valve16 while the sleeve 31 re-. mains stationary. This spring supporting sleeve structure is known inthe governor art and forms no part of the novelty of the present invention and accordingly need not be further illustrated ordescribed herein.

. From the foregoing it will be clear that any tendency of centrifugal force to move. the flyweights outwardly,

upon increase in speed of the shafts and 15, tends to move the pilot valve 16 downwardly in the bore of shaft 15. ,A decrease in speed; evidenced by a tendency, of the flyweights to move inwardly toward the shaft results in raising of the pilot valve under the impetus of coil, spring 30. The pilot valve; 16 rotates jointly with shaft 15. but is free to move. axially therein as here indicated.

The necessary hydraulic pressure required'for operation of the governor is provided by a pump indicated at 35 which' may be arranged to be driven from shaft 10 by a pair of gears 37 and 38.. The; pump 35 is preferably of the reversible type wherein the output is uni-directional regardless of the direction of rotation of the pump drive means. The outlet side of pump 35 communicates by means of a conduit 40,, with an annular passage 41 formed in support 14. and extending about the shaft 15,

whereby conduit: 30. has continuous and uninterrupted communication with the space between valve heads 17 and 13 by way of a series of peripheral openings. 42 in shaft 15. r

The housing 14 hasa pair of passages 47 and 48 and shaft 15 is provided with'peripheral openings 49; and 50 which are normally'axially in register with the valve heads 17 and 18 and. also register axially with the passages 47 and 48 of housing 14, as illustrated in the drawing. The exterior periphery of .shaft '15'at openings 49 and St) is grooved as at51 and 52 'so as to maintain conport the upper end of extension coil springStlin such manner that the latter may be axially adjusted at its 'upper end'to vary its resilient bias and the spring supporting means. of sleeve 31'is also'provided with antinecessaryslowing of shaft 10'to its desired speed level. At the same time that conduit 48 is connected with fluid pressure supply conduit 40,'conduit 47 is connected with outlet passages 60 by reason of the lowering .of.

valve head 17. This permits discharge of fluid from the space above piston 54 in chamber 53 through outlet passage- 65. l

The casing 32 which houses the governor mechanism itself comprises a reservoir or sump for pump and all of the discharge outlets of the system discharge into the interior of casing 32 where they gravitate to the sump forreuse by the pump. In the form of governor illustrated herein the level. of oil in casing 32 is maintained somewhat as indicated at 70 so that all passages which may take in fluid are submerged in the hydraulic medium.

Pilot valve 16 is further provided at its lower end with a piston head 71 which cooperates with the lower por:

tion of the bore of shaft 15 to form a fluid pressure chamber 72. V g

Shaft 15 has one or more radial passages 79 terrninat ing in a peripheral groove 80' which place the fluid pressure chamber 72 in continuous fluid communication with a passage 85 in housing 14. Passage 85 terminates in an adjustable restricted orifice by reason of a needle valve .90 which extends into passage 85 and is adjusted 'to more or less block the same by means of a threaded.

connection-'91 in housing 14. It will be noted that the outer end of passage 85 is continuously submerged in the Z hydraulic medium 70. V a

A cylinder 93 is removably fixed to housing 14 and its lower end is provided with 'a passage 94 which con-- nects the interior of cylinder 93 with passage 85. lA-

compensating piston 96 is disposed in cylinder 93 between a pair of precompressed coil springs 97 and 98, the; latter seating against the bottom of cylinder 93 and the former seating upwardly against a piston or seat member tinuous communication between passages 49 and 50and passages 47 and 48-, respectively, during rotation of shaft Passages 47 and 48 communicate, respectively, with f the upper and lower sides of a cylindrical chamber 53 7 formed in-housing 14. A power or actuating piston54 serves as a regulating member and is disposed in chamber 53 and has a piston rod/55; which connects pivotally with the outer end of an arm 56 fixedto shaft 11-. In this way axial movement of piston 54 in chamber 53 directly produces rotative regulating movementof-shaft 1'1 and thus the movements of piston 54 in chamber 53 directly determine and reflect the fuel setting 'of shaft 11, or any 55 leading outwardly therefrom. The lower out-let passage 61 likewise communicates with. an internal annular groove 67 formed in casing 14 and has free communication with the eneral interior of casing 32 by way of an outlet passage 68.

it will be seen from the foregoing that in a general way cceleration of shaft '10 will increase the centrifugal force on fiyweights 20 and urge pilot valve 16' downward. The consequent lowering of valve head 18 connects pres sure supply conduit with conduit 48, thus directing fluid pressure against the lower' side of. piston 54'. This corrective movement rotates shaft 11' in a counterclockwise direction to decrease the fuel setting, in instances where an engine is being governed','to accomplish the Piston 100 is pivotally connected to the lower end of" V V a link 101 by means of a piston rod 102 and the upper end of link 101. is pivotally connected with a slide 104 formed in an arm 105 fixed to throttle shaft 11. .This

pivotal connection is designated lfifiand may be adjusted l along slide 1tl4 to vary the'effective lever arm of arm 105., Piston 100 is vented as at to permit free expansionand contraction of the space above compensation piston 96.

The operation of the foregoing governor compensating Q and proportiomng surge chamberstructure :will now be described, bearing inmind that therud-imenta-ry governor operation involving. merely the centrifugally cont-rolled pilot valve and the throttle controlling power piston is conventional and has 'been'described earlie-r'herein. It

will be noted that pilot piston chamber 72 and the space 7 below compensating piston 96 in cylinder 93 are in free and continuous communication, and that the only external ingress or egress of fluid to the joint chamber thus formed is by way of the restricted orifice which is under the control of needle valve 90. V K

The piston 96 and its associated mechanism serve V twofold function as compensating means and as a proportionin-g surge. chamber. If we ignore other influences. forlthe moment, for ease and clarity of description, it will be noted. that piston 96, being held between the balanced springs 97 and 98, will move up and down in response to up and down movements of the piston or seat member 1 100, in direct proportion, eachmovement of seat member 100 being accompanied by a similar movement of piston 96 of one half the'amount of the movement'of sea-t member 100. The movementof seat member 100 by arm 105 is, in turn, under direct-control of the power piston 54 and is in direct proportion to movements of the latter, the ratio depending on the adjustment of the pivot 106 along slot 104.

If springs 97 and '98 were extremely stiif, so that they operated only to directly proportion the movement of compensating piston 96 to the movements of power piston 54, the compensating means thus provided would be particularly adapted to slow speed engines with heavy flywheels and proportionately slow response. The degree of governor response to a change in engine speed can be reduced to any desired speed of correction by adjustment "of the needle valve 90.

If the load on the engine being governed is reduced, its

speed tends to increase and .the consequent outward urge of flyweights moves pilot valve 16 downward. This movement is resisted by the fluid under piston head 71 in chamber 72, .its only mode of egress being past the restricted orifice in passage 85 formed by needle valve 90. In addition to this fluid resistance, downward movement of the pilot valve connects pressure from conduit to the under side of power piston 54, causing upward movement of power piston 54 and consequent proportionate downward movement of seat member 100. This increases the compression on spring 97 whereby it exceeds the compression of spring 98 and applies a resilient downward urge on compensating piston 96, tending to produce spring seat fluid flow from beneath piston 96 in compensating cylinder 93. I Again, because of the restriction interposed by needle valve '90, this movement tends to force fluid into chamber 72 and thus moves the pilot valve upward until movement of power piston 54 stops. The needle valve thus acts as a restrictive bypass, and, depending upon its adjustment, the power piston 54 will move a degree sufficient to return the pilot valve 16 to neutral position.

At this point in the operation movement of the power piston and pilot valve are stopped but the engine, while approaching its initial speed because of the amount of adjustment imparted to rock shaft 11 by movement of power piston '54, has not gone down to initial speed. During this period the pilot valve is pushing down on the compensating fluid in chamber 72 with a force corresponding to the amount that the engine is ofi speed, and this force causes leakage past the needle valve while the engine is coming back to speed, thespeed of such leakage being sufficient to prevent the pilot valve from moving away from neutral in the opposite direction.

If the throttle adjustment eflected by the power piston 54 in the foregoing manner proves insuflicient, the pilot valve again moves downwardly to further adjustment the power piston, such further adjustment being of lesser degree than the first because the engine has partially returned to proper speed and the relative unbalance of the flyweight force is correspondingly less.

Upon an increase in load on the engine, a reverse governor operation takes place. The pilot valve 16 rises and power piston '54 moves downwardly. This tends to enlarge both the chamber 72 beneath pilot valve 16 and the space below piston 96 in compensating cylinder 93. Thus, flow of fluid in passage 85 is from outside of housing 14 into the compensating cylinder 93, the outlet end of passage 85 being submerged in hydraulic medium as heretofore described. The operation is otherwise the same in theory as upon reduction in load on the engine.

It will be noted from a study of the foregoing that the restricted orifice controlled by needle valve 90 serves a threefold function. First, it acts as a dashpot to regulate the initial pilot valve movement upon a deviation in speed of the engine being governed. Second, it serves as a by-pass to regulate the time period which will elapse before compensating fluid from compensating cylinder 93 will raise the pilot valve 16 to neutral position and thus proportions the degree of governing movement of the power piston. Third, it serves as a time delay means during the period when the pilot valve is in neutral and motionless While the engine is responding to the completed adjustment of the power piston 54, preventing the pilot valve from opening in the opposite direction.

The system has thus far been described without considering the yieldability and energy storing potentials of the springs 97 and 98 and, as described, is complete and operative for certain general purposes and to meet certain.

However, undersets of operating conditions and factors. certain conditions of use, the foregoing hydraulic governor system without the energy storing capabilities of the springs 97 and 98, cannot be properly adjusted or proportioned to satisfactorily meet operating requirements.

The yieldable energy storing nature of these 'springs and the manner in which they modify the operation of compensating piston 96 constitute, in effect, refinements or additions to the general governor construction, arrangement and operation thus far described. These modifica- 'tions in the operation of the foregoing basic governor arrangement extend the usefulness of the underlying system to applications :and fields of usefulness for which the governor system Without the compensating piston springs would be inadequate.

Compensating piston 96 will normally assume a neutral midposition in cylinder 93, the pre-compressed springs 97 and 98 being of like characteristics. The push-pull action of the balanced force of the springs 97 and 98 on piston 96 causes the chamber beneath the piston in cylinder 9'3 to serve as an accumulator in either direction, positively or negatively, from the neutral position where the forces of springs 97 and '98 are in equilibrium.

This accumulator action is particularly well suited to modern high speed engines with quick response to throttle adjustment wherein there is less tendency for the governor to operate too fast and cause hunting. This accumulator action imparts greater flexibility of operation and the more yieldable nature of the forces imposed on the pilot valve by the compensating system gives the pilot valve more flexibility in producing control changes in the position of the power piston.

The compensating piston element 96 may comprise a diaphragm or any equivalent expansible chamber member and, instead of the balanced compensating piston springs described above, a single normally neutral or unstressed compression-extension coil spring of the push-pull type may be used in conjunction with the compensating piston or its equivalent exp-ansible chamber member.

What is claimed is: V

1. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chamber and a piston movable directly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, a compensating chamber and a piston therein movable to compress and expand said compensating chamber, said two chambers being in continuous fluid communication, an adjustable leakage orifice leading from the fluid system including said two chambers to a source of fluid under substantially no pressure, resilient means acting on said compensating piston for yieldably tending to retain the same in a neutral position, and means movable by and with the regulator member and acting upon said resilient means to vary the neutral position of said compensating piston in response to movement of said regulator member.

2. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chamber and a piston movable directly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, a compensating chamber and a piston therein movable to compress and expand said com-pensating chamber, said two chambers being in continuous fluid communication, an adjustable leakage orifice leading from the fluid system including said two chambers to a source of fluid under substantially no pressure, resilient means acting on said compensating piston for yieldably tending to retain the 7 same in a neutral position, means movable by the regu lator memb'er in'. direct proportion to movements thereof and 'acting'upon said resilient nzeans to varythe neutral position of said compensating piston in response to movement of said regulator member, and means for adjustably varying the ratio or" said proportion-ml'y movable means;

said regulator member in opposite directions, a fluid pressure chamber and a piston movable directly with saidpilot' valve for compressing. and expanding said chamber upon movement ofthepilot vaive in opposite directions, a cornpress and expand said compensating chamber, said two' sure chamber and a piston movable directly with said pilot' 7 valve for compressing andexpanding said chamber upon movement of the pilot valve in opposite directions, a com: pensating chamber and a piston therein movable to compress and expand said compensatingichamber, said two chambers being in continuous fluid communication, an adjustable leakageorifice leading from'the fluid system including. said two chambers to a source of fluidunder substantially no, pressure, resilient means acting on said compensating piston for yieldably tending to retain the same. against movement in either direction from a neutral position, and means movable by the regulator member and acting upon said resilient means to vary the resilient bias thereof in response to movement of said regulator member and thus vary said neutral position. 7

4. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable-in opposite directions to connect said fluid pres-sure source to move said regulator member in opposite directions,;a fluid pressure chamber and a piston movable directly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite'directions, a compensating. chamber and a piston therein movable to cornpress and expand said compensating chamber, said two chambers being in continuous fluid communication, an

adjustableleakage orifice leading from the fluid system including said two chambers: 'to'a source of fluid under substantially no pressure, resilient means acting on said compensating piston for yield-ably tending .to retain the 7 same against movement in either directionfrom a neutral, 7

position, means movable by the regulator member and acting upon said resilient means to vary the resilient bias thereof iii-response to'movement of said regulator memher-and thus vary said neutral position, and means for adjustably varying the ratio of movement of said movable means in response to movement of saidregulator member.

5. A hydraulic governor comprising a hydraulic pres sure operated regulator member, a source of operating fluid pressure therefor, a pilot valve'rnovable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chamber and a piston mov'abledirec-tly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, a compensa't-in-g chamber anda piston therein movable to compress and expand said compensating chamber, said two chambers being in continuous fluid; communication, an adjustable leakage orifice leading from the fluid system including said two chambers t-o'a source of fluid under substantially no pressure, resilient means acting on said compensating piston for yieldably tendingto retain the "same ina neutral position, and means movable by and with the regulator member and acting upon said resilient means to-vary the neutral position of said compensating piston in response to movement of said regulator member, said movable'means acting to yieldably compress said compensating chamber upon compressing movement of said pilot valve piston and yieldably expand. the same upon expanding movement of said pilot valve piston.

- 6. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite. directions to connect said fluid pressure source to move pensating chamber and a piston therein movable to c'om chambers beingin continuous fluid communication, an

adjustable leakage orifice leading from the fluid systemf including said two chambers to a source of fluid under substantiall'y no pressure, normally balanced opposed springs 7. A hydraulic governor comprising ahydraulic pressure operatedregulator member, a source of operat-iiig fluid pressure therefor, apilot valve movable in opposite directions toconnect said fluid pressure source to move said regulator member in opposite directions, a fluid pres-- sure chamber and a piston movable directly withsaid pilot valve for compressingand expanding said chamber upon movement of the pilot valve in opposite directions, a com-.-

pensating chamber and a piston therein movable to compress and expand said compensating chamber, said two chambers being in continuous fluid communication, an

adjustable leakage orifice leading from the fluidsystem including said; two'chambers to a source of fluid under substantially no pressure, normally balanced opposed springs acting against opposite sides of said compensating piston for yield-ably retaining the same in a neutral position, and means movable by and with theregulator member and acting against one of'said springs to 'vary'the neutral posit-ion of said compensating piston in response to move ment of said regular member. V v v V V 8. A hydraulio'governorcomprising a hydraulic pressure opera-tedregulator member, a source of operating fl'uidpressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member" in opposite directions, a fluid pressure chamber and a piston movable directly with said pilot 7 valve for compressing andexpanding said chamber upon movement of the pil'ot valve-in opposite directions, a" compensating chamber and a piston therein movable to compress; and expandi said compensating chambensaid two chambers being in continuous fluid communicatioii an adjustable leakage orificeleadingjfrom the fluid system including said two chambers to a source of fluid under substantially no pressure, normally balanced opposed springs acting against opposite sides of said compensating piston for 'yieldably retaining the same in aneutral pos ition, means movable by and with the regulator member and acting againstrone oisaid springs to vary the neutral position of saidcompensating piston in response to movement'of said regulator member, and means for adjustably varying the ratio or" movement of said movable member in response to; movement of said regulator member.'

9-. A hydraulic governor comprising a'hydraulic pres sure operated regulato'r'member, a source of operating fluid pressure therefor, a pilot valve movabie in opposite directions to connect said fluid pressure source'to move said regulator member in opposite'directions, a fluid pressure chamber'and a piston movable directly with said pilot valve for compressing and expanding said vchamber upon movement of the pilot valve in oppositedirections, a

compensating chamber and a piston therein movable to compress. and expand said compensating; chamber, said two chambersbeing in continuous fluid communication, resilient rneans acting on said compensatingpiston for yieldably tending to. retainthe same in a neutral position, and means movable by and with the regulator'member 9 and acting upon said resilient means to vary the resilient bias thereof in response to movement of said regulator member.

10. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chamber and a piston movable directly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, an accumulator chamber including a movable wall member and resilient means normally retaining said wall member in a neutral position, said accumulator chamber being in free fluid communication with said fluid pressure chamber, an adjustable leakage orifice leading from the fluid system comprising said fluid pressure chamber and said accumulator chamber, and means movable by the regulator member and acting on said resilient means to vary the neutral position of said movable wall member in response to movement of said regulator member.

11. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chamber and a piston movable directly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, an accumulator chamber including a movable wall member and resilient means normally retaining said Wall member in a neutral position, said accumulator chamber being in free fluid communication with said fluid pressure chamber, and means movable by the regulator member and acting on said resilient means to vary the neutral position of said movable wall member in response to movement of said regulator member.

12. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chamber and a piston movable directly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, a compensating chamber and a piston therein movable to compress and expand said compensating chamber, said two chambers being in continuous fluid communication, resilient means acting on said compensating piston for yieldably tending to retain the same in a neutral position, means movable by and with the regulator member and acting upon said resilient means to vary the resilient bias thereof in response to movement of said regulator member, and means for adjustably varying the proportion of relative movements as between said movable means and said regulator member.

13. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chamber and a piston movable directly with said 10 pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, an accumulator chamber including a movable wall member and resilient means normally retaining said wall member in a neutral position, said accumulator chamber being in free fluid communication with said fluid pressure chamber, means movable by the regulator member and acting on said resilient means to vary the neutral position of said movable wall member in response to movement of said regulator member, and means for adjustably varying the proportion of relative movements as between said movable means and said regulator member.

14. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chmber and a piston movable directly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, an accumulator chamber including a movable wall member and resilient means normally retaining said wall member in a neutral position, said accumulator chamber being in free fluid communication with said fluid pressure chamber, an adjustable leakage orifice leading from the fluid system comprising said fluid pressure chamber and said accumulator chamber, and means movable by the regulator member and acting on said resilient means to vary the neutral position of said movable wall member in response to movement of said regulator member, said movable means acting to yieldably compress said accumulator chamber upon compressing movement of said pilot valve piston and yieldably expand the same upon expanding movement of said pilot valve piston.

15. A hydraulic governor comprising a hydraulic pressure operated regulator member, a source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator member in opposite directions, a fluid pressure chamber and a piston movable directly with said pilot valve for compressing and expanding said chamber upon movement of the pilot valve in opposite directions, an accumulator chamber including a movable wall member and resilient means normally retaining said wall member in a neutral position, said accumulator chamber being in free fluid communication with said fluid pressure chamber, and means movable by the regulator member and acting on said resilient means to vary the neutral position of said movable wall member in response to movement of said regulator member, said movable means acting to yieldably compress said accumulator chamber upon compressing movement of said pilot valve piston and yieldably expand the same upon expanding movement of said pilot valve piston.

References Cited in the file of this patent UNITED STATES PATENTS 2,312,464 Ziebolz Mar. 2, 1943 2,623,503 Parker Dec. 30, 1952 2,623,504 Rodeck Dec. 30, 1952 

